The present invention relates to a polyamide/aliphatic polyester block copolymer, a process for the production thereof and a blend containing the same. More specifically, it relates to a polyamide/aliphatic polyester block copolymer which exhibits excellent thermal stability and good melt-fluidity, a process for the production thereof and a blend containing the same.
Japanese Patent Publication No. 19265/1967 discloses a method in which a polyamide having terminal amino groups is melt-reacted under heat with a six- or seven-membered lactone such as .delta.-valerolactone or .epsilon.-caprolactone. The block copolymer obtained by this method has a softening point which shows that the degree of randomness is considerably high.
Japanese Patent Publication No. 29468/1969 discloses a method in which caprolactam and caprolactone are allowed to react in the presence of metal sodium to produce a polyester-polyamide copolymer. The polyester-polyamide copolymer obtained by this method shows the linearity in the relationship between the polymer composition and melting point as is described in the said Publication. Therefore, it is different from a typical random copolymer which shows a downward convex form in the above relationship, but it is a block copolymer whose randomness degree is considerably high.
Similarly to Japanese Patent Publication No. 29468/1969, Eur. Polym. J. Vol. 20, No. 6, pages 529-537 (1984) discloses a method in which .epsilon.-caprolactone and .epsilon.-caprolactam are polymerlzed in a ring-opening polymerization to produce a copolymer of polycaprolactone and polycaprolactam.
Japanese Patent Publication No. 26688/1982 discloses a method for producing a biodegradable polyester amide copolymer, in which a mixture of a polycaprolactone having a high molecular weight and an aliphatic polyamide having a high molecular weight is melted by heating it to a temperature equal to, or higher than, the melting points of these and the ester/amide exchange reaction is carried out until a product which shows a clear drop in melting point is obtained. The melting point of the copolymer disclosed in the said Publication shows that the said copolymer has a considerably high degree of randomness.
Japanese Laid-open Patent Publication No. 171731/1986 discloses a polycaprolactoneamide elastomer which contains 20 to 90% by weight of a polyamide component and 80 to 10% by weight of a polycaprolactone component and is excellent in impact absorption.
Japanese Laid-open Patent Publication No. 306229/1992 discloses a biodegradable polyesteramide copolymer which contains an aliphatic polyester block and an aromatic polyamide block and has a melting point lower than that of the aromatic polyamide used as a raw material. As a method for producing this biodegradable polyesteramide copolymer, the said Publication discloses a method in which a mixture of a polyester and a polyamide is allowed to react by heating it to a temperature equal to, or higher than, the melting or softening points of these in an inert gas until the formation of a product which shows a clear drop in melting point from the melting or softening points of these.
In the method of reacting polyester and polyamide in an ester/amide exchange reaction while they are melted, it is required to react them at a high temperature for a long period of time, and the productivity is hence very low, since polyamide and polyester are inherently incompatible with each other. Further, this method is also very disadvantageous in terms of energy since a copolymer is formed by sectioning the chain of a polymer once produced as one having a high polymerization degree.
Japanese Laid-open Patent Publication No. 156010/1993 discloses a method for producing a biodegradable polylactoneamide resin containing 5 to 70% by weight of polyamide units and 30 to 95% by weight of polylactone units, in which a polyamide-forming compound and a polylactone compound having an average molecular weight of at least 10,000 are allowed to react.
It is an object of the present invention to provide a novel polyamide/aliphatic polyester block copolymer.
It Is another object of the present invention to provide a polyamide/aliphatic polyester block copolymer whose randomness degree is highly inhibited and which therefore exhibits a remarkably high melting point over that of a random copolymer.
It is further another object of the present invention to provide a polyamide/aliphatic polyester block copolymer which has a high degree of block segment formation and whose polyamide and aliphatic polyester contents are inhibited to remarkably low degrees.
It is still further another object of the present invention to provide a process for producing the above polyamide/aliphatic polyester block copolymer of the present invention industrially advantageously.
It is yet another object of the present invention to provide a polyamide/aliphatic polyester block copolymer having the shape memory and restoration capability.
It is yet another object of the present invention to provide a resin blend containing the above polyamide/aliphatic polyester block copolymer of the present invention, e.g., a resin blend containing the above polyamide/aliphatic polyester block copolymer of the present invention as a compatibilizing agent for intimately mixing resins which are poor in compatibility to each other.
Other objects and advantages of the present invention will be apparent from the following description.
The above objects and advantages of the present invention are achieved, first, by a polyamide/aliphatic polyester block copolymer;
(A) comprising a polyamide block composed substantially of at least one of a recurring unit of the formula (1), ##STR1## wherein R.sub.1 is an alkylene group having 4 to 12 carbon atoms, and a recurring unit of the formula (2), ##STR2## wherein R.sub.2 is an alkylene group having 4 to 12 carbon atoms or an alkylene-arylene-alkylene group having 8 to 16 carbon atoms, and R.sub.3 is an alkylene group having 4 to 12 carbon atoms or an arylene group having 6 to 12 carbon atoms, PA1 (B) satisfying the following expression (5), EQU T.sub.1 -T&lt;100-C (5) PA1 wherein T is the melting point (.degree.C.) of the above block copolymer, T.sub.1 is the melting point (.degree.C.) of a polyamide composed of the polyamide block and C is the content (wt. %) of the polyamide block, PA1 (C) exhibiting the extraction amount which satisfies the expression (6), when extracted in tetrahydrofuran, EQU E&lt;(100-C).times.0.4 (6) PA1 wherein E is the extraction amount (wt. %) when the block copolymer is refluxed in tetrahydrofuran of which the weight is 100 times the weight of the block copolymer under heat for 2 hours, and C is the content (wt. %) of the polyamide block, PA1 (D) having an intrinsic viscosity, measured at 35.degree. C., in the range of from 0.5 to 5. PA1 wherein T is the melting point (.degree.C.) of the block copolymer, T.sub.1 is the melting point of a polyamide composed of the polyamide block and C is the content (wt. %) of the polyamide block. PA1 wherein T.sub.1, T and C are as defined in the expression (5). PA1 wherein E is the extraction amount (wt. %) when the block copolymer is refluxed in tetrahydrofuran of which the weight is 100 times the weight of the block copolymer under heat for 2 hours, and C is the content (wt. %) PA1 wherein E and C are as defined in the expression (5). PA1 (A) a polyamide composed substantially of at least one of a recurring unit of the formula (1), ##STR13## wherein R.sub.1 is an alkylene group having 4 to 12 carbon atoms, and a recurring unit of the formula (2), ##STR14## wherein R.sub.2 is an alkylene group having 4 to 12 carbon atoms or an alkylene-arylene-alkylene group having 8 to 16 carbon atoms, and R.sub.3 is an alkylene group having 4 to 12 carbon atoms or an arylene group having 6 to 12 carbon atoms, PA1 (B) at least one of an aliphatic polyester and .epsilon.-caprolactone PA1 (C) in the presence of an aromatic monohydroxy compound in an amount of 5 to 100 parts by weight per 100 parts by weight of the total amount of the above components (A) and (B) and in the presence of an ester interchange catalyst, and then distilling off the above aromatic monohydroxy compound. PA1 (A1) comprising a polyamide block composed substantially of at least one of a recurring unit of the formula (1) -a, ##STR16## and a recurring unit of the formula (2)-b, ##STR17## wherein k is an integer of 4 to 12 and p is an integer of 4 to 12, and a polycaprolactone block composed substantially of a recurring unit of the formula (3)-a, ##STR18## (B) satisfying the following expression (5), EQU T.sub.1 -T&lt;100-C (5) PA1 wherein T is the melting point (.degree.C.) of the above block copolymer, T.sub.1 is the melting point (.degree.C.) of a polyamide composed of the polyamide block and C is the content (wt. %) of the polyamide block, PA1 (E) exhibiting the melting point derived from the polycaprolactone block in the range of from about 40.degree. to 60.degree. C., and PA1 (F) having shape memory and restoration capability.
and an aliphatic polyester block composed substantially of at least one of a recurring unit of the formula (3), ##STR3## wherein R.sub.4 is an alkylene group having 1 to 12 carbon atoms, and a recurring unit of the formula (4), ##STR4## wherein R.sub.5 is an alkylene group having 2 to 12 carbon atoms and R.sub.6 is an alkylene group having 2 to 12 carbon atoms or a combination of an alkylene group having 2 to 12 carbon atoms and a divalent aromatic group,
and
FIG. 1 is the scanning electron microscopic photograph of a block copolymer (Example 1) of the present invention.
FIG. 2 is a scanning electron microscopic photograph of a conventional block copolymer (Comparative Example 1).
FIG. 3 shows the shape memory capability of a shape memory fiber (Example 21) obtained from a block copolymer of the present invention.
FIG. 4 is the shape memory capability of a shape memory fiber (Example 22) obtained from another block copolymer of the present invention.
The polyamide/aliphatic polyester block copolymer of the present invention is defined by the above requirements (A), (B), (C) and (D).
The requirement (A) defines that the above block copolymer of the present invention comprises a polyamide block composed essentially of at least one of the recurring unit of the formula (1) and the recurring unit of the formula (2) and an aliphatic polyester block composed substantially of at least one of the recurring unit of the formula (3) and the recurring unit of the formula (4).
In the formula (1), R.sub.1 is an alkylene group having 4 to 12 carbon atoms. This alkylene group may be linear or branched, while a linear alkylene group is preferred. Examples of this alkylene group include tetramethylene, pentamethylene, hexamethylene, decamethylene, undecamethylene and dodecamethylene. Of these, pentamethylene is preferred. When R.sub.1 is pentamethylene, the above formula (1) is represented by the following formula (1)-a. ##STR5##
Examples of the recurring unit of the above formula (1) further include ##STR6##
In the formula (2), R.sub.2 is an alkylene group having 4 to 12 carbon atoms or an alkylene-arylene-alkylene group having 8 to 16 carbon atoms, and R.sub.3 is an alkylene group having 4 to 12 carbon atoms or an arylene group having 6 to 12 carbon atoms.
The alkylene group having 4 to 12 as each of R.sub.2 and R.sub.3 may be linear, branched or cyclic.
Examples of each alkylene group above include tetramethylene, hexamethylene, octamethylene, decamethylene, dodecamethylene, neopentylene, 2,2,4-trimethylhexamethylene, 2,4,4-trimethylhexamethylene and 1,4-cyclohexylene.
Examples of the alkylene-arylene-alkylene group having 8 to 16 carbon atoms as R.sub.2 include p-xylylene, m-xylylene, ##STR7##
Further, examples of the arylene group having 6 to 12 carbon atoms as R.sub.3 include m-phenylene, p-phenylene, 2,6-naphthylene and 1,4-biphenylene.
Of these, hexamethylene is preferred as R.sub.2, and tetramethylene is preferred as R.sub.3. In this case, the above formula (2) is represented by the following formula (2)-a. ##STR8##
Examples of the recurring unit of the above formula (2) further include ##STR9##
In the present invention, the polyamide block is composed substantially of the recurring unit of the above formula (1) or is composed substantially of the recurring unit of the above formula (2) or is composed of the recurring unit of the above formula (1) and the recurring unit of the above formula (2).
In the aliphatic polyester block, R.sub.4 in the formula (3) is an alkylene group having 1 to 12 carbon atoms. This alkylene group may be linear or branched, while a linear alkylene group is preferred.
Examples of the above alkylene group include methylene, methylmethylene, tetramethylene, ethylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, decamethylene and undecamethylene. Of these, methylene, methylmethylene and pentamethylene are preferred. Pentamethylene is particularly preferred. In this case, the above formula (3) represents a caprolactone block of the following formula (3)-a. ##STR10##
In the formula (4), R.sub.5 is an alkylene group having 2 to 12 carbon atoms.
This alkylene group may be linear, branched or cyclic.
Examples of the above alkylene group include ethylene, trimethylene, tetramethylene, hexamethylene, octamethylene, decamethylene, dodecamethylene, neopentylene, 3-methylpentamethylene, 2,2,4-trimethylhexamethylene, 2,4,4-trimethylhexamethylene and 1,4-cyclohexylene.
In the formula (4), further, R.sub.6 is an alkylene group having 2 to 12 carbon atoms or a combination of an alkylene group having 2 to 12 carbon atoms with a divalent aromatic group.
Examples of each of the above alkylene groups having 2 to 12 carbon atoms include those described concerning R.sub.5 above.
In the combination of an alkylene group having 2 to 12 carbon atoms with a divalent aromatic group, the divalent aromatic group is preferably a subordinate component, and the content of the component unit from the divalent aromatic group on the basis of the total of the recurring units is preferably 30 mol % or less, more preferably 20 mol % or less, particularly preferably 10 mol % or less. Examples of the divalent aromatic group include ##STR11## in which M is an alkali metal atom, a quaternary ammonium group or a quaternary phosphonium group.
The block copolymer of the present invention, containing a small amount of the component from ##STR12## shows a low surface resistivity, has permanent antistatic properties and hence can be used as a permanent antistatic agent for other thermoplastic resins.
In the present invention, the aliphatic polyester block is composed substantially of the recurring unit of the above formula (3) or is composed substantially of the recurring unit of the above formula (4) or is composed substantially of the recurring unit of the above formula (3) and the recurring unit of the above formula (4).
In the block copolymer of the present invention, the content of the polyamide block is 5 to 90% by weight, and the content of the aliphatic polyester block is 95 to 10% by weight. Preferably, the content of the polyamide block is 7 to 85% by weight, and the content of the aliphatic polyester block is 93 to 15% by weight. Particularly preferably, the content of the polyamide block is 10 to 80% by weight, and the content of the aliphatic polyester block is 90 to 20% by weight.
The requirement (B) defining the block copolymer of the present invention shows that the randomness degree of the block copolymer of the present invention is highly inhibited.
That is, the requirement (B) defines that the block copolymer of the present invention satisfies the following expression (5). EQU T.sub.1 -T&lt;100-C (5)
T.sub.1 is a melting point of a polyamide comprising the polyamide block composed of at least one of a recurring unit of the formula (1) and a recurring unit of the formula (2).
Under the conditions satisfying the formula (5), preferably, the block copolymer of the present invention satisfies the following expression (5)-a. EQU T.sub.1 -T&lt;0.8(100-C) (5)-a
The requirement (C) defining the block copolymer of the present invention shows that the block copolymer has a high degree of block segment formation and that the aliphatic polyester content is inhibited to remarkably low degrees.
That is, the requirement (C) defines that the block copolymer of the present invention exhibits the extraction amount which satisfies the expression (6), when extracted in tetrahydrofuran, EQU E&lt;(100-C).times.0.4 (6)
of the polyamide block.
The above expression for example shows that when the polyamide block content is 50% by weight, the extraction amount in tetrahydrofuran is less than 20% by weight. An aliphatic polyester other than the block copolymer is not all that are included in the extract resulting from the extraction in tetrahydrofuran, while the extract at least includes an aliphatic polyester which does not constitute the block segment.
The block copolymer of the present invention preferably exhibits the extraction amount which satisfies the following expression, EQU E&lt;(100-C).times.0.3 (6)-a
The final requirement (D) defining the block copolymer of the present invention is that the block copolymer of the present invention has an intrinsic viscosity, measured in a phenol/1,1,2,2-tetrachloroethane mixed solvent (weight ratio 60/40) at 35.degree. C., in the range of from 0.5 to 5. This intrinsic viscosity at 35.degree. C. is preferably in the range of from 0.6 to 3.
The block copolymer of the present invention is used in a variety of fields as will be explained later. The block copolymer of the present invention also has its characteristic feature in that it is biodegradable.
According to the present invention, as a process for the production of a polyamide/aliphatic polyester block copolymer including the above block copolymer of the present invention, there is also provided a process comprising melt-reacting under heat
and
In the process of the present invention, the polyamide (A) and at least one component (B) of an aliphatic polyester and .epsilon.-caprolactone are allowed to react in the presence of an aromatic hydroxy compound and an ester interchange catalyst by melting these components under heat.
The polyamide used as a raw material is composed substantially of at least one of the recurring unit of the above formula (1) and the recurring unit of the above formula (2).
The above formulae (1) and (2) are already explained.
Examples of the above polyamide include nylon 6, nylon 66, nylon 610, nylon 612, nylon 11, nnylon 12, nylon MXD6, nylon 46, polyhexamethyleneisophthalamide, polytrimethylhexamethyleneterephthalamide and a copolyamide obtained by copolymerizing at least two of these polyamides. Of these, nylon 6 and nylon 66 are preferred as the polyamide. These polyamides may be used alone or in combination. These polyamides prepared, for example, for producing a fiber, a film or a plastic may be used as they are. The molecular weight of the polyamide is not specially limited, while it is preferred to use, for example, a polyamide having an intrinsic viscosity, measured in m-cresol at 35.degree. C., of approximately 0.3 to 3.0.
As the aliphatic polyester used as the other raw material, preferred is, for example, an aliphatic polyester composed substantially of at least one of the recurring unit of the above formula (3) and the recurring unit of the above formula (4).
Examples of the above aliphatic polyester include polycaprolactone, polypropiolactone, polyvalerolactone, polylactate, polyglycolate, polyethylene adipate, polyethylene succinate, polyethylene azelate, polyethylene sebacate, polytrlmethylene sebacate, polytetramethylene sebacate, polyhexamethylene sebacate, polyoctamethylene sebacate, polydecamethylene sebacate, polyneopentylene sebacate and a copolyester obtained by copolymerizing at least two of these aliphatic polyesters. Of these, preferred are polycaprolactone, polyethylene sebacate, polytetramethylene sebacate and polyneopentylene sebacate. These polyesters may be used alone or in combination.
The molecular weight of the aliphatic polyester is not specially limited, while it is advantageous to use, for example, an aliphatic polyester having an intrinsic viscosity, measured in a phenol/1,1,2,2-tetrachloroethane mixed solvent (weight ratio 60/40) at 35.degree. C., of approximately 0.03 to 3.0,preferably approximately 0.5 to 2.5.
In the process of the present invention, .epsilon.-caprolactone may be used in place of, or together with, the above aliphatic polyester.
In the process of the present invention, the weight ratio of the above polyamide/the aliphatic polyester and/or .epsilon.-caprolactone is preferably 5/95 to 90/10. When the proportion of the polyamide is less than 5, the resultant copolymer is poor in heat resistance. When it is greater than 90, the resultant copolymer is poor in properties exhibited by the copolymerization of the aliphatic polyester, such as biodegradability. The weight ratio of the polyamide the aliphatic polyester and/or .epsilon.-caprolactone is preferably 7/93 to 85/15, particularly preferably 10/90 to 80/20.
In addition, .epsilon.-caprolactone undergoes ring-opening polymerization during the reaction during the melt-reaction.
The aromatic monohydroxy compound used in the reaction has the function as a compatibilizing agent between the polyamide and the aliphatic polyester, and as a result, causes a reaction of a terminal amino group and/or a carboxyl group of the polyamide, and the aliphatic polyester or an amide/ester interchange reaction of the polyamide and the polyester, whereby the intended block copolymer can be effectively obtained.
As the aromatic monohydroxy compound, preferred is a compound of the formula (7), ##STR15## wherein X is an alkyl group having 1 to 3 carbon atoms or a halogen atom, and m is an integer of 0 to 3. Examples of the above monohydroxy compound includes phenol, m-cresol, p-cresol, o-cresol, 2,3-dimethylphenol, 2,4-dimethylphenol, 2,5-dimethylphenol, 2,6-dimethylphenol, 3,4-dimethylphenol, m-ethylphenol, o-ethylphenol, p-ethylphenol, p-propylphenol, o-propylphenol, m-propylphenol, o-chlorophenol, m-chlorophenol, p-chlorophenol, 2,4-dichlorophenol, 2,3-dichlorophenol, 2,5-dichlorophenol, and 2,4,6-trichlorophenol.
The amount of the aromatic monohydroxy compound per 100 parts by weight of the total amount of the polyamide and the aliphatic polyester and/or .epsilon.-caprolactone is 5 to 100 parts by weight. When the above amount of the aromatic monohydroxy compound is less than 5 parts by weight, undesirably, the function of the aromatic monohydroxy compound as the compatibilizing agent is insufficient. When the above amount is larger than 100 parts by weight, undesirably, the step of distilling off the aromatic monohydroxy compound after the polymerization takes a long period of time. The amount of the aromatic monohydroxy compound per 100 parts by weight of the total amount of the polyamide and the aliphatic polyester and/or .epsilon.-caprolactone is preferably 10 to 50 parts by weight.
The temperature for the reaction under heat is not specially limited, and it is sufficient to use a temperature at which the polyamide and the aliphatic polyester are dissolved or melted in the polymerization system. The temperature for the reaction is preferably 180.degree. to 320.degree. C., more preferably 200.degree. to 300.degree. C.
For promoting the above reaction, a catalyst is added to the melt-reaction system. The catalyst is selected from those known as an ester interchange catalyst. Examples of tile catalyst preferably include alkali metal compounds, alkaline earth metal compounds and compounds of metals such as titanium, tin, zinc, antimony, manganese, cobalt and germanium. The amount of the catalyst is not specially limited, while it is preferably approximately 0.0001 to 0.1% by weight based on the block copolymer to be formed.
The time for the melt-reaction is not specially limited and differs depending upon the polymer composition and polymerization temperature, while it is approximately 30 minutes to 5 hours.
In the process of the present invention, the polyamide and at least one of the aliphatic polyester and .epsilon.-caprolactone are melt-mixed/reacted whereby the block copolymer can be obtained. As a final step, however, it is required to substantially remove the above aromatic monohydroxy compound from the polymerization system by distilling it off. The method for removing the aromatic monohydroxy compound includes a method in which the melting temperature is increased higher than the boiling point of the aromatic monohydroxy compound under the polymerization conditions. A method in which the pressure is reduced at the later-stage of the reaction is effective for decreasing the boiling point of the aromatic monohydroxy compound and distilling it off, and it can be preferably carried out. By removing the aromatic monohydroxy compound, there can be obtained the block copolymer composed substantially of the polyamide and the aliphatic polyester.
For the atmosphere for the polymerization, it is preferred to use an atmosphere of an inert gas such as nitrogen or argon under atmospheric pressure or elevated pressure at an initial stage of the reaction, and gradually decrease the pressure at a later stage of the reaction.
According to studies of the present inventors, It has been revealed that some of block copolymers that can be produced by the process of the present invention have the shape memory capability.
That is, according to the present invention, there is further provided a polyamide/polycaprolactone block copolymer;
The above block copolymer comprises a polyamide block composed substantially of at least one of the recurring unit of the formula (1)-a and the recurring unit of the above formula (2)-b and a polycaprolactone block composed substantially of the recurring unit of the above formula (3)-a.
The recurring unit of the formula (1)-a is a unit from the ring-opening of .epsilon.-caprolactam.
In the formula (2)-b, k is an integer of 4 to 12, and p is an integer of 4 to 12. Examples of --(CH.sub.2).sub.k -- and --(CH.sub.2).sub.p -- include tetramethylene, hexamethylene, octamethylene, decamethylene and dodecamethylene.
As the polyamide to compose the polyamide block, nylon 6 and nylon 66 are preferred.
The recurring unit of the above formula (3)-a is a unit from the ring-opening of caprolactone.
In the above block copolymer, preferably, the content of the polyamide block is 5 to 60% by weight, and the content of the polycaprolactone block is 95 to 40% by weight.
When the above content of the polyamide block is less than 5% by weight or larger than 60% by weight, the shape memory and restoration capability is insufficient. The polyamide block/polycaprolactone block weight ratio is preferably 7/93 to 50/50, more preferably 10/90 to 40/60.
In the above block copolymer, the length of each of the above polyamide block and polycaprolactone block is not specially limited, while these blocks preferably have chain lengths to such an extent that the melting point derived from the polycaprolactone and the melting point of the polyamide can be distinguishably observed when the block copolymer is thermally analyzed by DSC.
In the above block copolymer having the shape memory capability, the melting point (T) of the block copolymer and the melting point (T.sub.1) of the polyamide block composing the block copolymer have the relationship which satisfies the above expression (5), preferably the above expression (5)-a.
The above block copolymer having the shape memory capability is required to have a melting point, derived from the polycaprolactone block, in the range of from approximately 40.degree.to 60.degree. C.
The above block copolymer has an intrinsic viscosity in the range of 0.5 to 5.0 when measured in a phenol/1,1,2,2-tetrachloroethane mixed solvent (weight ratio 60/40) at 35.degree. C. When this intrinsic viscosity is less than 0.5, undesirably, the block copolymer is insufficient in mechanical properties and the shape memory and restoration capability. When it is higher than 5.0, undesirably, the moldability is poor.
The block copolymer having the shape memory capability can be properly produced by the already described method of the present invention.
A fiber having the dimension memory and restoration capability, i.e., a shape memory fiber, can be obtained by melt-spinning the above block copolymer having the shape memory capability.
The shape memory fiber of the present invention can be obtained by melt-spinning the above block copolymer. The above shape memory fiber can be produced by a known method in which a molten polymer is extruded through a spinning nozzle by means of a plunger method or extrusion method melt-extruder and the extrudate is cooled and solidified to form a fiber.
The temperature for melting the above polymer is preferably approximately between T.sub.1 (melting point) of the polyamide component composing the block copolymer and 320.degree. C., particularly preferably between about (T.sub.1 of the polyamide component +10).degree.C and about 300.degree. C. The draft ratio for the spinning is preferably at least 5, particularly preferably at least 10.
The dimension memory fiber of the present invention may be a monofilament or a multlfilament. The denier of the fiber is not specially limited, while the denier of a single yarn is preferably approximately 1 to 200.
The dimension memory fiber of the present invention exhibits the shape memory capability while it is in the state of an as-spun yarn, and it can be used as it is. For obtaining the higher shape memory capability, it is preferred to draw the as-spun yarn 1.5 to 6 times and subjecting the drawn yarn to a relaxation treatment at a temperature equal to, or higher than, 60.degree. C. and lower than the T.sub.1 (melting point) of the polyamide component. This treatment removes the strain which remains in the as-spun yarn obtained by the melt-spinning, and improves the shape memory capability.
The temperature for the above drawing is not specially limited, while it is preferably approximately between 0.degree. and 100.degree. C., more preferably 20.degree. and 80.degree. C. The draw ratio is preferably 1.5 to 6. When the draw ratio is less than 1.5, undesirably, it is difficult to draw the fiber uniformly. When the draw ratio is greater than 6, undesirably, the fiber is liable to break. The draw ratio is more preferably 2 to 5.
Then, the drawn yarn is subjected to a relaxation treatment at a temperature equal to, or higher than, 60.degree. C. and lower than the T.sub.1 of the polyamide component. When the temperature for the relaxation treatment is lower than 60.degree. C., it is not sufficient to remove the strain of the as-spun yarn. When it is equal to, or higher than, the T.sub.1 of the polyamide component, the polyamide undergoes melting. The temperature for the relaxation treatment is preferably between 60.degree. C. and (T.sub.1 of polyamide component -20).degree.C., particularly preferably between 60.degree. C. and (T.sub.1 of polyamide component -40).degree.C.
The relaxation conditions are not specially limited, while the above drawn yarn may be relaxed under limitation or relaxed under no tension. It is preferably relaxed under no limitation and no tension. It may be drawn and relaxed by a known method using the take-up rate difference of rollers.
The dimension memory fiber of the present invention is constituted of a polyamide and polycaprolactone which are excellent in heat resistance and moldability, and is remarkably excellent in melt-spinnability.
Using a polyamide crystal phase as a fixed phase and a polycaprolactone crystal phase as a reversible phase, the shape memory fiber of the present invention is excellent in shape memory and restoration capability, and also excellent in durability in repeated use.
Due to the above properties, the shape memory fiber of the present invention can be used as a fiber material, a fabric and component for composite fibers. The above block copolymers of the present invention, including the block copolymer having the shape memory capability, exhibit excellent affinity to a thermoplastic resin which has no or poor compatibility with a polyamide since they have a polyamide block and an aliphatic polyester block.
According to the present invention, therefore, there is further provided an intimate blend comprising a thermoplastic resin having no or poor compatibility with a polyamide, a polyamide resin and the block copolymer of the present invention as a compatibilizing agent, and there is also provided an intimate blend comprising a thermoplastic resin having no or poor compatibility with a polyamide and the block copolymer of the present invention.
Typical examples of the above thermoplastic resin include a polyester resin, a polycarbonate resin, a polyester carbonate resin, a polystyrene-containing resin and a polyphenylene oxide resin.
The above polyester resin is obtained by the polycondensation of an aromatic dicarboxylic acid and a diol.
Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid and 5-carboxy-3-(4'-carboxyphenyl-1,1,3-trimethylindane. These aromatic dicarboxylic acids may be used alone or in combination. Particularly preferred are terephthalic acid, isophthalic acid and naphthalene-2,6-dicarboxylic acid.
Examples of the diol include glycol, hydroquinone, resorcinol, dihydroxydiphenyl, bis(hydroxyphenyl)-alkane. bis-(hydroxyphenyl)cycloalkane, bis(hydroxyphenyl)-sulfide, bis(hydroxyphenyl)-ether, bis-(hydroxyphenyl)-ketone, bis-(hydroxyphenyl)-sulfone, bis-(hydroxyphenyl)-sulfoxide, pentamethyl-(hydroxyphenyl)-indanol, .alpha., .alpha.'-bis-(hydroxyphenyl)-diisopropylbenzene, and compounds prepared by alkylating or halogenating the benzene ring(s) of these compounds. Typical examples which are most generally used are ethylene glycol, butylene glycol and 2,2-bis(4-hydroxyphenyl)propane (to be abbreviated as "bisphenol A" hereinafter). The above diols may be used in combination.
For obtaining a resin composition (blend) having desirable properties, it is preferred to use a polyester having an intrinsic viscosity, measured in a phenol/1,1,2,2-tetrachloroethane mixed solvent (weight ratio 60/40) at 35.degree. C., of at least 0.4.
The above polycarbonate resin is obtained from a diphenol or its derivative and carbonic acid or its derivative.
Examples of the diphenol include hydroquinone, resorcinol, dihydroxydiphenyl, bis(hydroxyphenyl)-alkane. bis-(hydroxyphenyl)-cycloalkane, bis(hydroxyphenyl)-sulfide, bis(hydroxyphenyl)-ether, bis-(hydroxyphenyl)-ketone, bis-(hydroxyphenyl)-sulfone, bis-(hydroxyphenyl)-sulfoxide, pentamethyl-(hydroxyphenyl)-indanol, .alpha., .alpha.'-bis-(hydroxyphenyl)-diisopropylbenzene, and compounds prepared by alkylating or halogenating the benzene ring(s) of these compounds. The most generally and typically used is "bisphenol A". The above diphenols may be used in combination.
In addition to the carbonic acid or its derivative, a small amount of other aromatic or aliphatic dicarboxylic acid or its derivative may be used as a comonomer.
The derivatives of the diphenol and carbonic acid refer to esters, salts and halides of these.
For obtaining a resin composition (blend) having desirable properties, it is preferred to use a polycarbonate having a viscosity-average molecular weight of 15,000 to 40,000.
Polystyrene-containing resin includes acrylonitrile styrene, acrylonitrile butadiene styrene, etc.
Further, the above polyester carbonate resin, polystyrene-containing resin and polyphenylene oxide resin do not have to be any special ones, and can be selected from general resins known per se.
In the above intimate blend containing the block copolymer of the present invention as a compatibilizing agent, the amount of the block copolymer of the present invention per 100 parts by weight of the total of the above thermoplastic resin and the polyamide resin is preferably 1 to 50 parts by weight, more preferably 2 to 40 parts by weight, particularly preferably 3 to 30 parts by weight.
In the above case, the thermoplastic resin/polyamide resin weight ratio is preferably 95/5 to 5/95, more preferably 90/10 to 10/90.
The polyamide resin as an object includes a variety of polyamide resins obtained by the polycondensation of a three- or more-membered lactam, .omega.-aminocarboxylic acid, dibasic acid and diamine.
Specifically, the polyamide resin includes polymers of .epsilon.-caprolactam, aminocaproic acid, enatholactam, 7-aminoheptanoic acid and 11-aminoundecanoic acid, and polymers or copolymers obtained by the polycondensation of diamines such as butanediamine, hexamethylenediamine, nonamethylenediamine, undecamethylenediamine and m-xylylenediamine and dicarboxylic acids such as terephthalic acid, isophthalic acid, adipic acid, sebacic acid, dodecanoic dibasic acid and glutaric acid.
More specifically, the polyamide resin includes aliphatic polyamide resins such as nylon 6,nylon 46, nylon 66, nylon 610, nylon 11, nylon 12, nylon MXD6 and nylon 612, and aromatic polyamides such as polytrimethylhexamethyleneterephthalamide and polyhexamethyleneisophthalamide.
The polyamide resin used in the present invention preferably has an intrinsic viscosity in the range of from 0.5 to 3.0, as an index for molecular weight, when measured in m-cresol at 35.degree. C.
In the intimate blend containing the thermoplastic resin and the block copolymer of the present invention, the amount of the block copolymer of the present invention per 100 parts by weight of the thermoplastic resin is preferably 1 to 200 parts by weight, more preferably 2 to 100 parts by weight.
The above two intimate blends of the present invention may contain fibrous reinforcing materials such as a glass fiber, a metal fiber, an aramid fiber, a ceramic fiber, potassium titanate whisker, a carbonate fiber and asbestos, and various fillers such as talc, calcium carbonate, mica, clay, titanium oxide, aluminum oxide, glass flakes, a milled fiber, metal flakes and a metal powder as required. Further, the two intimate blends of the present invention may contain at least one of additives such as a heat stabilizer, an oxidation stabilizer, a light stabilizer, a lubricant, a pigment, a flame retarding agent and a plasticizer.
The method for producing the above intimate blends of the present invention is not specially limited, while they can be easily produced by melt-kneading the above various resins, the block copolymer of the present invention and optionally the above various additives, etc.